Oil burning hot-air furnace



Jan. 1, 1952 w. c. ROBERTS 2,581,145

OIL BURNING HOT AIR FURNACE 2 SHEETSSHEET 1 Filed Sept. 5, 1947 FIG. 1

INVENTOR. W. C. ROBERTS ATTORNEY Jan. 1, 1952 Filed Sept. 5, 1947 w. c. ROBERTS OIL BURNING HQT AIR FURNACE 2" SHEETS--SHEET 2 21 FIG. 3 26 20 i l8 l8 v I {'zr fin 57 i 1 I 5| 56 HI 24 52 i 36 I OIL II LEVEL I r I if Ill'll W W M l i Z i 5 \E" M? may 3 INVENTOR.

W. C. ROBERTS ATTORNEY Patented Jan. 1, 1952 OIL BURNING HOT-AIRFURNACE William 0. Roberts, Detroit, -Mich., assignor to Bone Tool & '.Gauge Company, Detroit, :Mich.,-a

corporation of Michigan Application September 5, 1947jSerial No. 772,255

This invention relates to heating and more particularly to a furnace unit including a'liquid fuel burner.

Oil burners and furnace structures for use with oil burners have heretofore been made and used incorporating a plurality of flue and air passageways in relatively expensive constructions with utilization of numerous types of airpassageways, both for the burner and the heated air in struc-- tures of complicated design and configuration Without creating a maximum of heat efficiency or reducing the cost of manufacture. In addition one of the primary faults with previous burners of the character as herein described has been their failure to support combustion by i properly supplying air thereto.

It is therefore among the objects of this invention to provide an improved furnace structure; an improved and efiicient oil burner construction which is capable of utilizing commercial fuel oils of a character as low as grade number 3 at their maximum heating efiiciencies; the combination of a furnace and oil burner structure which is simple in design, heats with maximum efficiency and yet is produced at a minimum of cost; and, to provide an oil furnace and burner structure of compact nature to serve as a central heating unit.

Further objects and advantages of the invention will be apparent from the following specification taken in conjunction with the accompanying drawings, wherein; r

Fig. l is a perspective in partial sectionof'my improved oil burner and furnace structure;

Fig. 2, an isometric view in partial section of the oil burner fire box;

Fig. 3, a cross sectional plan view of the oil burner fire box and its insert assembly;

Fig. 4, a cross sectional view taken on theline 4-4 of Fig. 3;

Fig. 5, a cross sectional view taken on the line 5-5 of Fig. 3.

With reference to the drawings, 'for purpose of illustration the'heating unit is shown as installed under floor I!) and comprises an outer heavy steel'casing ll of sheet material bent to a rectangular shape and having its joined edges welded in an overlapping flange [-2. The casing II is closed at its base portion by plate 13 provided with illustrative openings or holes M and open at its top portion, over which is placed a floor grill or register IS in alignment with the floor structure l0. Within-the rectangular outer casing :l I is a rectangular air flow shield 16 'open at its top and bottom portions which are in 1 Claim. (01.126-116) spaced relationship to grill l5 and base, plate 16, and held from contact withthe-casing II by one or more suitable brackets ll on each side to form or provide inlet air fi'ow passageways it for comparatively or relatively cool air to enter the heating unit of the furnace structure during "its heating operation. The shield l6 is'provided about its upper portion with the inturned angular flange ['9 which directs a downward flow of air through the passageways t8 and further tends to keep the heated air rising from passageways -2lland 2 l segregated from the incoming relatively cold air in passageways [8.

Within the air flow shield I8 is a rectangular fire-chamber 22 likewise spaced from the air shield it by suitable-spaced bra'ckets, as illustrated at H, to provide air up-flow passageways 29. The fire-chamber '22 is supported above the bottom by suit-able bloclzs or angle iron supports 23 in order to permit circulation of incoming and outgoing air throughout the passageways as illustrated and described. An outlet flue 24 leading from the lower portionof fire-chamber 22 and extending through outer casing it passes under a cut-out portion 25 of shield l6 and supports one end of the shield I6 thereby.

'Within the walls of the fire chamber 22, exposed to the direct heat of the fire, there is positioned a rectangular flue or air flow duct 26 containing air flow passageway 2| exposed at its lower portion to the incoming air from air passageway l8 andopen atits top end to expel superheated air substantially centrally through the air register it. The rectangular air flue 26, in passing through the fire-chamber 22, is spaced from the-walls of the .firechamber 22 .to provide a suitable space through which 'theheated prodnets of combustion may circulate directly from a .heatsource, about the flue Zfi, .to superheat thejair as it flows therethrough adjacent to the direct flame of the heat source andsubstantially throughout its path of travel in counterfiow to the heated products .of combustion.

Adjacent to the base of air flue .26, a rectangular closed force-draft conduit 21 formed :by walls 28, 29, 30 and 3'! is inserted adjacent base portion of fire chamber 22 throughaaconduit .32 and supports a rectangular oil burning firepot or box assembly within the walls of the fire chamber '22. This firebox is supported by the side walls 28 of rectangular enclosed conduit "21; its end wall it and its top 39 is partially covered by a rectangular cover or'bafile plate :33, 6 inches x 9 inches :in outside diameter, fastened by suitable bolt means 34 in top and flanges and 3| formed by the appropriate turned edges of the walls 29 and 29 respectively. The plate 33 is provided with a narrow, centrally positioned longitudinal slot 3'!, which is 5 inches x 1% inches in size, integral depending flanges 38 and 39 spaced A; inch inwardly at the lower curved edge of the slotted opening 31 and extending downwardly 3 inches from the top of plate 33. The receptacle 49, baffle plate 33 with its depending flanges 33 form a rectangular firepot or box closed at its ends by solid walls 39 and with the side portions 38 containing 15 equally spaced slots 48, each of which is g; inch in width and 2% inches in length with an open space of 8 4 inch between each kerf.

As is more clearly shown in Figs. 2 and 5, the inner surface portion 42 of depending flanges 38 and 39 are inclined upwardly at a slight angle from their base, adjacent the base portion of receptacle All, to form at their top edges a narrowed mouth ending in the inwardly extending curved lip 33 which projects inch inwardly and is curved upwardly from the inner peripheral top portion of the depending flanges 38 and 39. The lowermost surface of the lip 43 is angled inwardly and upwardly toward the top of the fire-pot at an approximate angle of 110 with its inner peripheral edge rounded so that the inclined surfaces 42 of walls 38 and 39 act in conjunction with dip 83, causing in effect, with forced draft, flame concentration during a burning operation.

The depending flanges 39 and 39 extend into and against the locating ridges or buttons 44 pcsitioned in the corners at the base of oil receptacle 49, and have a clearance about their outer periphery of inch with respect to the sides of the receptacle 49. The oil receptacle 49 is supported from bailie plate 33 by bolts 45 in cars 46 with the bolts 45 being threaded to provide a clearance of 1 inch between the upturned bafllelike sides of receptable 49 and the plate 33. A suitable fuel oil composition capable of being volatilized for burning is supplied to the sump 1 from oilline 4B and adapted to be thinly spread over the area 49, forming the base portion of receptacle 40, between the flanges 38 wherefroin it burns in a manner as hereinafter described. 7

Conventional apparatus providing for the automatic operation and control of the fuel supply and blower may be provided for use with the furnace described. It is contemplated that a fuel supply valve unit or oil control 5| receiving oil by means of a feed line 60 may be employed in association with a thermostatic device 53 positioned within the furnace anda thermostat, not shown, located in the space being heated, such as a room. It is also contemplated that means for varying the speed of a blower 52 may be provided in association with the oil level control 5| and the thermostatic elements previously mentioned. The controls referred to may regulate the flow of fuel including shutting off the supply ata predetermined temperature of either thermostatic element or, adjusting the supply in accordance therewith.

The blower unit 52 is mounted by ring 55 on plate 55 which constitutes an end closure member for conduit 21 and is attached to the outer casing II by suitable bolt and screw means 51. The valve unit 5!, blower unit 52, control box 59, and thermostatic element 53 are conventional structures which operate in a conventional man- 4 not, through control cables 58 and 59 in that they are supplied with electrical energy from a conventional junction box (not shown) operated from a conventional hand switch (not shown) located in any position desired and suitable to an operator. The operating circuit is an interrelated control arrangement having suitable conventional time delay and current relay devices for controlling the operation of the automatic blower 52 in conjunction with the flow of oil from feed line 60 to the oil line 48. That is, upon the starting operation the speed of the blower is reduced until the oil is afiame and thereafter the speed of the bloweris regulated in accordance with the degree of heat required or in other words in proportion to the quantity of oil fuel supplied to the base 41 of receptacle 49.

With the burner in operation and the blower 52 forcing air through the duct 21 a regulated preheated forceful draft is created through the burner by reason of the air passing over the upright sides of the receptacle 49 which form in effeet with the depending flanges 38 and 39 a series of compression nozzles 41 from which the air is emitted through each of the diametrically opposed slots 4| in equal and opposite directions and force; The upper open area portion of the slots 4| forming evenly spaced direct admission ports causing relatively horizontal opposed air stream to flow into the burner space and the lower portion of the same slots, enclosed in spaced relationship to the upright sides of receptacle 49, forming indirect air ports and causing somewhat downwardly directed opposed heated air streams to fiowagainst the surface of the fuel oil.

It has been found that by this arrangement, a more complete mixing of incoming air and gases from the evaporating oil is obtained producing a bright hot flame structure capable of vaporizing low grade fuel oils which burn. This flame burns within the fire-box formed by the slightly angled surfaces 42 and projects from the mouth of the burner formed by the curved lip 43 substantially without leaving any deposit of soot or carbon either within the fire chamber 22 or about the space within the which the furnace structure is placed, This complete combustion of a fuel oil is believed to be provided by a complete mixing of opposed vertical and somewhat angular forced streams of air with the gases vaporized from the oil by turbulence of conflicting streams of air through slots 4! and the heat of combustion within the firepot. That is, the position and size of the kerfs or slots permit a turbulation by a combination of turbulence and heat and fuel atomization.

While the above description is concerned with an improved furnace heating device started by turning on the hand switch, opening the hinged door 6! and thrusting a flame into the incoming oil it will be apparent that a conventional spark gap ignition device or other conventional starting device, as a pilot or the like, may be used for igniting the oil and the unit made completely automatic by substitution of a thermostatic control for the hand operated switch. Further that by proper adjustment of the valve unit automatic ignition means for starting the burner may be utilized with appropriate automatic controls.

As will be apparentfrom the above description, another of the features of the improved furnace structure is that instead of forming the walls of the numerous flat surface portions from a continuous metal sheet welded at the juncture of their meeting ends, the entire portion of the furnace structure may be built from a plurality of cut and fitted fiat metal sheets which are welded at their joining edges. Further that a furnace structure of the character as herein described will permit of installation with the maximum of 621 ciency as related to standard floor construction and that its installation does not interfere or weaken supporting members of the building.

It will be obvious to those skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof and therefore the invention is not limited by that which is shown in the drawing and described in the specification but only as indicated in the appended claim.

What is claimed is:

The combination of a rectangular casing open at the top and closed at the bottom, a register mounted at the top of said casing, a substantially rectangular combustion chamber structure having top, bottom, side, and end walls within said casing substantially parallel to and in spaced relation to the register, the bottom, and the walls, respectively of said casing, a conduit extending from said chamber through an end wall of said casing and providing communication between the exterior of said casing and said chamber for the admission and removal of an oil burning fire pot, an elongated oil burning fire pot in said chamber adjacent the bottom and said end wall and having a flame outlet slot in substantially parallel relation to the side walls of said chamber, means to supply combustion air through said conduit to said fire pot, means to supply oil to said fire pot, a substantially rectangular air flow duct open at the top and bottom having the walls thereof substantially parallel to opposed walls of said chamber, said duct extending through said combustion chamber from the bottom through the top of said chamber providing communication be-- tween the bottom space and the top space lying between the tops and bottoms of said casing and chamber, an outlet flue extending from the other end wall of said chamber adjacent the bottom thereof and extending through the corresponding end wall of said casing, a substantially rectangular shield open at the top and bottom surrounding the walls of said chamber with the walls of said shield substantially parallel to and spaced from the corresponding walls of said chamber and said casing, the open top and bottom of said shield being spaced from the top and bottom of said casing whereby air may circulate between the shield and the casing downwardly and between said chamber and said shield upwardly through said register.

WILLIAM C. ROBERTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 516,363 Calkins Mar. 13, 1894 1,522,802 Buff Jan. 13, 1925 1,643,115 Field et a1. Sept. 20, 1927 1,936,003 White Nov. 21, 1933 2,072,048 Leonard Feb. 23, 1937 2,162,410 Stephens .2 June 13, 1939 2,171,917 DeLin Sept. 5, 1939 2,391,585 Miller Dec. 25, 1945 FOREIGN PATENTS Number Country Date 533,502 Germany Sept. 15, 1931 

